Combustion switch



Aug. 24, 1937. A. L. RUBEL COMBUSTION SWITCH Original Filed Oct. 16, 1933 r w W F J 3 grdkam 1k. Ewe! [j 1 fi ht 14 Patented Aug. 24, 1937;

COMBUSTION SWITCH Abraham L. Rubel, Boston, Mass., assignor to Penn Electric Switch 00., Des a corporation of Iowa Moines, Iowa,

Original application October 16, 1933, Serial No.

693,800, now Patent No. 2,022,826, dated December 3, 1935. Divided and this application October 28, 1935, Serial No. 47,134

9 Claims.

An object of my present invention is to provide a combustion switch of simple, durable and inexpensive construction, particularly adapted for use in connection with an electric control apparatus for fuel burners, as disclosed in my copending application Serial No. 693,800, filed October 16, 1933, now Patent No. 2,022,826, De-

cember 3, 1935, from which application the present one is a division. I

A further object is to provide a combustion switch which operates to terminate operation of the ignition mechanism of a burner, the combus tion switch including a lost motion connection to delay the terminating operation of the switch.

A further, object is to provide a combustion switch having a friction connection for one of the movable contacts and a lost motion connection in conjunction with the usual slippable connection of a combustion switch which provides I an explosion upon such re-energization.

A further object is to provide a combustion switch having inherent means for delaying the termination of the ignition period of a burner for a time period after the combustion chamber 5 of the furnace begins to heat up, such delay being especially desirable forthe rotary type of oil burner requiring a long ignition period for insuring combustion.

Still a further object is to provide a combustion switch which is operable to de-energize a relayswitch having the peculiarity of operating for this purpose as it moves from cold to hot position and then starts to return toward cold position, such peculiarity being effected by a 4,5 frictional mounting for one of the contacts of the switch.

With these and other objects in view my invention consists in the 'construction, arrangement and combination of the various parts of my device, whereby the objects contemplated are attained, as hereinafter more fully set forth,

pointed out in my claims and illustrated in the accompanying drawing, in which:

Figure 1 is a sectional view through a combus- 66 tion switch, embodying'myinvention.

Figure 2 is a front elevation on the line 2-2 of Figure 1 showing the switch therein and its operating mechanism; and

Figures 3 to 10 inclusive show the operation of the switch diagrammatically in its various positions from warming up position'to cold position.

On the accompanying drawing I have used the reference numeral 10 to indicate a switch housing. It is providedwith the usual cover plate A hub I4 thereon rotatably journals a rod I6 which is responsive to the coiling and uncoiling of a bimetal temperature responsive member l8. One end of the bimetal element or coil [8 is anchored to the hub |4.as by a screw 20, the other end being secured by a screw 22 to the outer end of the rod Hi.

My combustion switch is adaptable for mounting in the usual manner on the stack of a furnace with the bimetal coil I 8 projecting into the 20 stack so that it is responsive to the combustion in the furnace.

Withinthe housing 10, I provide a toothed wheel. or disc 24 loosely mounted on the rod Hi. It is provided with a pair of pins 26 and 28 and the rod l6.is provided with a pin 30 to cooperate therewith. The pins 26, 28 2 1d 30 provide a lost motion connection between the temperature rotated rod 16 and the toothed wheel 24.

A spring arm 32 has one end suitably anchored 30 in a block of insulation 33 and thereby supported by the casing l0 and its other end projecting to ward the toothed wheel and engaging the teeth thereof, as shown in Figure 2. It will be obvious that rotation of the toothed wheel in one direction or the other will first swing the spring arm 32 from the full line position of Figure 2 to either of the dotted. line positions and further rotation of the toothed. wheel is then possible without any appreciable movement of the spring arm 32, which will snap over the successive teeth of the wheel as the wheel is further rotated.

Other spring arms 34, 36 and 38 are each an- -chored at one end in the insulating block 33 held by a 'rivet 46 anda friction spring washer 48 against the surface of the insulating block 33. By such mounting the arm 40 can be moved either upwardly or downwardly and will remain in any position to which it is moved, whereas the other arms 32, 34, 36, and 38 tend to spring back to the position of Figure 2.

The arms 32, and 36 carry contacts 66 while the arms 36 and it carry contacts 52 and the arms 36 and 36 carry contacts 56, all adapted to engage and separate from each other in different positions-of the switch structure. In the application from which the present application is a division, the contacts. 56 were provided for establishing a. starting circuit of a burner while the contacts 52 and 56 were provided for delo energizing a relay upon engagement and de-energizing ignition mechanism upon engagement respectively, although. these contacts can be provided for any other purpose desirable, the construction and operation of the switch per se being the invention in the present application. 'l'he parent application contained circuit claims for the specific circuits controlled by the switch.

Practical operation 0 In the operation of my switch structure, the parts are in the position of Figure 10 when the switch is cold. Upon combustion occurring the rod 56 moves in the direction'of the arrow a (see Figure 2) first permitting the spring arm 32 to rotate the notched disc from the positionof Figure 10 to the position of Figure 2, in which latter position the starting contacts 56 are open. The lost motion connection is then taken-up when the pin is moved from the pin 26 to 30 the pin 28, as shown in Figure 3 and finally picks up the pinv 28 and rotates the disc as in Figure 4, which, however, accomplishes no result as the contacts all still remain open, the contacts 52 both being moved downwardly by a pair'of projections 56 and 58 engaging the frictionally pivoted arm ii] and the spring arm 36 and moving them downwardly.

The projections 56 and 58 are carried by the arm 66 connected with the spring arm 32 and extending laterally therefrom and the projections engage insulating extensions 62 and 66 of the spring arms 60 and 36. As the stack continues to heat up the contacts 66 will finally be made as in Figure 5 and thus terminate the ignition period which has been extended over the usual time period provided by combustion switches of the slippable connection type by the time period required for taking up the 10st motion. Obviously, the distance between the pins 26 and 26 can be increased to extend the timing period and decreased to shorten it.

Figure 5 illustrates the final position of the switch contacts, further heating of the stack merely operating the slip connection without producing any result.

Upon combustion failure the rod I6 will rotate reversely, first separating the contacts 5 as in Figure 6 and at the same time leaving the switch arm in the position it assumed in 60 Figure 5 and, permitting the switch arm 36 to move toward it.

Eventually the contacts 52 will be made as in Figure 7 for de-energizing the relay when the switch is connected as in the parent application,

after which further rotation of the rod through the position of Figure 8 will produce no result and finally after the lost motion is taken up the contacts 52 will be separated as in Figure 9 and .in the final cold position the contacts 50 will be made as in Figure 10, thus recycling the-burner by again establishing the control circuit. the reverse movement of the rod l6 as shown in Figures '7, 8, and 9 the lost motion again provides an extended period of time, this period hemg the purging period between flame failure aoamci and re-establishment of the burner circuit. Thus the lost motion connection is important in both the movement of the-switch'to hot position and to cold position.

The peculiaraction of the switch arms 35 and 60 produces no change in the circuit controlled by the contacts 52 while the combustion switch is moving from cold to hot position but when moving from hot to cold position, a circuit is both made as in Figure '7 and broken as in Figure 9. This provides for deenergizing the relay by engagement of the contacts 52 and opening of these contacts for further automatic operation of the burner control after the cold position of Figure 10 is assumed, all of this occurring in the case of combustion failure.

When there is no combustion failure and the combustion switch returns from the hot position to the cold position because of'opening of the room thermostat, the contacts 52 will engage and separate but cause no operation because the burner circuit has been rendered dead by the room thermostat.

Some changes may be made in the 'construc-- tion and arrangement of the parts of my device without departing from the real spirit and pur pose of my invention and it is my intention tocover by my claims, any modified forms of structure or use of mechanical equivalents, which may be reasonably included within their scope.

I claim as my invention:

1. In a combustion switch, a temperature responsive movable element, an operating element operated thereby, a switch arm connected with said operating element by a slippable connection and a pair of switch contacts controlled by said switch arm, both of said contacts being moved in one direction but kept separated throughout the entire movement of said switch arm in one direction and one of said contacts being moved to engage the other one and then the other one being moved to disengage said one of said contacts, both upon' movement of said switch arm in the other direction.

2. In a, combustion switch, a temperature responsive movable element, an operating element operated thereby, a switch arm connected with said operating element by a slippable connection, a pair of contact arms, contacts carried thereby and'normally separated from each other, one of said contact arms being frictionally pivoted, said switch arm moving both of said contact arms in one direction to maintain said contacts separated upon movement of the switch arm in one direction and moving the other of said pair of contact arms without moving the frictionally pivoted one to cause engagement of the contacts switch arm, both of said contacts being moved in one direction but kept separated throughout the entire movement of said switch arm in one direction, one of said contacts being moved to en-' gage the other one and then the other one moved to disengage said one of said contacts, both upon movement of said switch arm in the other direction and a lost motion connection between said operating element and said switch arm.

4. In a combustion switch, a temperature responsive movable element, an operating element operated thereby, a switch arm connected with said operating element by a slippable connection,

a pair of contact arms, contacts carried thereby and normally separated from each other, one 01' said contact arms being frictionally pivoted, said switch arm moving both of said contact arms in one direction to maintain said contacts separated upon movement of the switch arm in one direction and moving the other of said pair of contact arms without moving the frictionally pivoted one to cause engagement of the contacts and then moving the frictionally pivoted contact arm to separate the contacts from each other upon movement of said switch arm, in the other direction and a lost motion connection between said operating element and said switch arm. 5. In a switch structure, a condition responsive movable element, a switch arm operatively connected with said condition responsive element and a .pair of contact arms controlled by said switch arm, one of said contact arms being frictionally pivoted, said switch arm moving both of said contact arms in one direction to maintain said contacts separated upon movement of the switch arm in one direction and moving the other of said pair of contact arms without moving the frictionally pivoted one to cause engagement of the contacts and then moving the frictionally pivoted contact arm to separate the contacts from each other upon movement of said switch arm in the other direction.

6. In a switch structure, a condition responsive movable element, a toothed disc operatively connected therewith, a spring arm anchored at one end and having its other end extending toward said disc and engaging the teeth thereof and a 49 switch controlled by said switch arm, said switch comprising a pair of contact arms, contacts carried thereby and normally separated from each other, one of said contact arms being frictionally pivoted, said spring arm moving both of said con- 45 tact arms in one direction to maintain said con' tacts separated upon movement of the spring arm in one direction and moving the other of said pair of contact arms without moving the frictionally pivoted one to cause engagement of said 50 contacts and then moving the frictionally pivoted contact arm to separate said contacts upon movement of the switch arm in the other direction.

'7. In a switch structure, a condition responsive movable element, a toothed disc operatively connected therewith by a lost motion connection, a spring arm anchored at one end and having its other end extending toward said disc and engaging the teeth thereof and a switch controlled by said switch arm, said switch comprising a pair of contact arms, contacts carried thereby and normally separated from each other, one of said contact arms being frictionally pivoted, said spring arm moving both of said contact arms in A one direction to maintain said contacts separated upon movement of the spring arm in one direction and moving the other of said pair of contact arms without moving the frictionally pivoted one to cause engagement of said contacts and then moving the frictionally pivoted contact arm to separate said contacts upon movement of the switch arm in the other direction.

8. In a control switch, an oppositely moving actuating element, a pair of contacts engaged and separated thereby and means to prevent engagement thereof throughout the entire movement of said actuating element in one direction and said contacts successively engaged and separated substantially immediately upon movementof said actuating element in an opposite direction from any position thereof because of movement in said one direction.

9. In a control switch, an oppositely moving actuating element, a pair oi contacts to be engaged and separated thereby and means to prevent engagement when the actuating element moves in one direction andto cause successive engagement and separation when the actuating element moves in an opposite direction, said means comprising a spring mounting for one of said contacts and a frictional pivot mounting for the other one, said actuating element, when moving in the first mentioned direction, engaging said spring mounted contact to move it in a separating direction and said frictionally mounted contact to move it in an engaging direction and when moving in the second mentioned direction permitting said spring mounted contact to engage said irictionally mounted'contact and the actuating element then engaging the fn'ctionally mounted contact and moving it in a separating direction.

ABRAHAM L. RUBEL. 

